Dataset Information

Structural and enzymatic characterization of the sialidase SiaPG from Porphyromonas gingivalis.

ABSTRACT: The sialidases, which catalyze the hydrolysis of sialic acid from extracellular glycoconjugates, are a group of major virulence factors in various pathogenic bacteria. In Porphyromonas gingivalis, which causes human periodontal disease, sialidase contributes to bacterial pathogenesis via promoting the formation of biofilms and capsules, reducing the ability for macrophage clearance, and providing nutrients for bacterial colonization. Here, the crystal structure of the P. gingivalis sialidase SiaPG is reported at 2.1 Å resolution, revealing an N-terminal carbohydrate-binding domain followed by a canonical C-terminal catalytic domain. Simulation of the product sialic acid in the active-site pocket together with functional analysis enables clear identification of the key residues that are required for substrate binding and catalysis. Moreover, structural comparison with other sialidases reveals distinct features of the active-site pocket which might confer substrate specificity. These findings provide the structural basis for the further design and optimization of effective inhibitors to target SiaPG to fight against P. gingivalis-derived oral diseases.

SUBMITTER: Dong WB

PROVIDER: S-EPMC10071834 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature

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Structural and enzymatic characterization of the sialidase SiaPG from Porphyromonas gingivalis.

Dong Wen Bo WB Jiang Yong Liang YL Zhu Zhong Liang ZL Zhu Jie J Li Yang Y Xia Rong R Zhou Kang K

Acta crystallographica. Section F, Structural biology communications 20230330 Pt 4

The sialidases, which catalyze the hydrolysis of sialic acid from extracellular glycoconjugates, are a group of major virulence factors in various pathogenic bacteria. In Porphyromonas gingivalis, which causes human periodontal disease, sialidase contributes to bacterial pathogenesis via promoting the formation of biofilms and capsules, reducing the ability for macrophage clearance, and providing nutrients for bacterial colonization. Here, the crystal structure of the P. gingivalis sialidase Sia ...[more]

PMID: 36995120

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Project description:Porphyromonas gingivalis is an important human pathogen and also a model organism for the Bacteroidetes phylum. O-glycosylation has been reported in this phylum with findings that include the O-glycosylation motif, the structure of the O-glycans in a few species, and an extensive O-glycoproteome analysis in Tannerella forsythia. However, O-glycosylation has not yet been confirmed in P. gingivalis. We therefore used glycoproteomics approaches including partial deglycosylation with trifluoromethanesulfonic acid as well as both HILIC and FAIMS based glycopeptide enrichment strategies leading to the identification of 257 putative glycosylation sites in 145 glycoproteins. The sequence of the major O-glycan was elucidated to be HexNAc-HexNAc(P-Gro-[Ac]0-2)-dHex-Hex-HexA-Hex(dHex). Western blot analyses of mutants lacking the glycosyltransferases PGN_1134 and PGN_1135 demonstrated their involvement in the biosynthesis of the glycan while mass spectrometry analysis of the truncated O-glycans suggested that PGN_1134 and PGN_1135 transfer the two HexNAc sugars. Interestingly, a strong bias against the O-glycosylation of abundant proteins exposed to the cell surface such as abundant T9SS cargo proteins, surface lipoproteins, and outer membrane β-barrel proteins was observed. In contrast, the great majority of proteins associated with the inner membrane or periplasm were glycosylated irrespective of their abundance. The P. gingivalis O-glycosylation system may therefore function to establish the desired physicochemical properties of the periplasm. IMPORTANCE Porphyromonas gingivalis is an oral pathogen primarily associated with severe periodontal disease and further associated with rheumatoid arthritis, dementia, cardiovascular disease, and certain cancers. Protein glycosylation can be important for a variety of reasons including protein function, solubility, protease resistance, and thermodynamic stability. This study has for the first time demonstrated the presence of O-linked glycosylation in this organism by determining the basic structure of the O-glycans and identifying 257 glycosylation sites in 145 proteins. It was found that most proteins exposed to the periplasm were O-glycosylated; however, the abundant surface exposed proteins were not. The O-glycans consisted of seven monosaccharides and a glycerol phosphate with 0-2 acetyl groups. These glycans are likely to have a stabilizing role to the proteins that bear them and must be taken into account when the proteins are produced in heterologous organisms.

Dataset Information

Structural and enzymatic characterization of the sialidase SiaPG from Porphyromonas gingivalis.

Publications

Structural and enzymatic characterization of the sialidase SiaPG from Porphyromonas gingivalis.

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